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  Table of Contents  
SNIPPETS
Year : 2014  |  Volume : 32  |  Issue : 4  |  Page : 471-473
 

Research snippets


Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Karond Bhopal, Bhopal, India

Date of Submission21-Sep-2014
Date of Acceptance21-Sep-2014
Date of Web Publication4-Oct-2014

Correspondence Address:
P Desikan
Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Karond Bhopal, Bhopal
India
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Source of Support: None, Conflict of Interest: None


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How to cite this article:
Desikan P. Research snippets . Indian J Med Microbiol 2014;32:471-3

How to cite this URL:
Desikan P. Research snippets . Indian J Med Microbiol [serial online] 2014 [cited 2019 Oct 16];32:471-3. Available from: http://www.ijmm.org/text.asp?2014/32/4/471/142247


Three persons died of suspected cholera in Mirdhapara village, Odisha, India. They died within a span of a few hours on Wed, 10 th September, 2014. (http://timesofindia.indiatimes.com/city/bhubaneswar/3-die-of-cholera-in-Bargarh-district/articleshow/42329932.cms). Pandemic Vibrio cholerae strains in the O1 serogroup have 2 biotypes: classical and El Tor. Atypical El Tor strains are categorised into 2 groups: Wave 2 and Wave 3 strains, based on genomic variations and the CTX phage that they harbour. Whole-genome analysis of V. cholerae strains in the seventh cholera pandemic has demonstrated gradual changes in the genome of prototype and atypical El Tor strains, indicating that atypical strains arose from the prototype strains by replacing the CTX phages. A study examined the molecular mechanisms that affected the emergence of El Tor strains with classical cholera toxin-carrying phage. The results implied that the Wave 2 and Wave 3 strains may have been generated from intermediary strains in nature. Prototype El Tor strains can become Wave 3 strains by excision of CTX-1 and re-equipping with the new CTX phages. The data suggest that inter-chromosomal recombination between 2 types of CTX phages is possible when a host bacterial cell is infected by multiple CTX phages (PLoS Pathog. 2014 Sep 18;10 (9):e1004384. doi: 10.1371/journal.ppat. 1004384. eCollection 2014)

An attempt was made to describe the aetiology, clinical features and socio-demographic background of adults with diarrhoea attending different urban and rural diarrhoeal disease hospitals in Bangladesh. Between January 2010 and December 2011, a total of 5054 adult diarrhoeal patients aged >20 years were enrolled into the Diarrhoeal Disease Surveillance Systems at four different hospitals (two rural and two urban) of Bangladesh. It was found that middle-aged and elderly patients were more likely to present to rural diarrhoeal disease facilities than urban ones. V. cholerae was the most commonly isolated pathogen (16%) followed by rotavirus (5%), enterotoxigenic  Escherichia More Details coli (ETEC) (4%) and Shigella (4%). Of these pathogens, V. cholerae (19% vs. 11%, P < 0.001), ETEC (9% vs. 4%, P < 0.001), and rotavirus (5% vs. 3%, P = 0.013) were more commonly detected from patients presenting to urban hospitals than rural hospitals, but Shigella was more frequently isolated from patients presenting to rural hospitals than urban hospitals (7% vs. 2%, P < 0.001). The isolation rate of Shigella was higher in the elderly than in younger adults (8% vs. 3%, P < 0.001). (Epidemiol Infect. 2014 Sep 15:1-11. [Epub ahead of print])

A loop-mediated isothermal amplification (LAMP) assay for  Salmonella More Details detection targeting bcfD gene, a conserved fimbrial operon gene existing in Salmonella, was developed and validated. The assay successfully amplified 44 Salmonella strains (14 standard strains and 30 clinical isolates), but none of 9 non-Salmonella standard strains (Proteus mirabilis, Listeria monocytogenes, E. coli, Pseudomonas aeruginosa, Shigella flexneri, Shigella sonnei, Klebsiella pneumoniae, Campylobacter jejuni and Vibrio parahemolyticus). The detection limit was 5 CFU of Salmonella pure culture or 200 CFU of artificially spiked faeces/per reaction system (equivalent to 5,000 CFU/g of faeces). It was found that this method could directly detect Salmonella in chicken faeces free of pre-enrichment in a reaction time of 25 minutes. It was concluded that the LAMP method is a rapid, sensitive, specific and practical method for Salmonella detection (Lett Appl Microbiol. 2014 Sep 9. doi: 10.1111/lam. 12328. [Epub ahead of print])

A study compared the ability of four commercially available media for screening extended-spectrum beta-lactamase (ESBL) to detect and identify ESBL-producing Salmonella and Shigella in faecal samples. A total of 71 Salmonella and 21 Shigella isolates producing ESBLA and/or AmpC, were received at Norwegian Institute of Public Health between 2005 and 2012. The 92 isolates were mixed with faecal specimens and tested on four ESBL screening media; ChromID ESBL (BioMèrieux), Brilliance ESBL (Oxoid), BLSE agar (AES Chemunex) and CHROMagar ESBL (CHROMagar). The total sensitivity (ESBLA + AmpC) with 95% confidence intervals after 24 hours of incubation were as follows: ChromID: 95% (90.4-99.6), Brilliance: 93% (87.6-98.4), BLSE agar (Drigalski): 99% (96.9-100), BLSE agar (MacConkey): 99% (96.9-100) and CHROMagar: 85% (77.5-92.5). It was concluded that all four agar media were reliable in screening faecal samples for ESBLA-producing Salmonella and Shigella. However, only ChromID and BLSE agar gave reliable detection of AmpC-producing isolates. Identification of different bacterial species based on colony colour alone was not accurate for any of the four agars (BMC Microbiol. 2014 Sep 4;14 (1):217. [Epub ahead of print])

Comparative studies of the associations between different infectious diseases and climate variability, such as the El Niño-Southern Oscillation, are lacking. Diarrhoeal illnesses, particularly cholera and shigellosis, provide an important opportunity to apply a comparative approach. Cholera and shigellosis have significant global mortality and morbidity burden, pronounced differences in transmission pathways and pathogen ecologies, and there is an established climate link with cholera. In particular, the specific ecology of V. cholerae is often invoked to explain the sensitivity of that disease to climate. In this context, the extensive surveillance data of the International Centre for Diarrhoeal Disease Research, Bangladesh, were used to revisit the known associations between cholera and climate, and to address their similarity to previously unexplored patterns for shigellosis. A similarity in association patterns was found, which suggested a systemic breakdown in population health with changing environmental conditions, in which climate variability acted primarily through increasing the exposure risk of the human population (PLoS One. 2014 Sep 17;9 (9):e107223. doi: 10.1371/journal.pone. 0107223. eCollection 2014)

Vibrio cholerae
experience a temperature shift as the bacteria move from contaminated water at lower temperatures to a temperature of 37°C in the human intestine. Within the intestine, V. cholerae express cholera toxin (CT) and toxin-coregulated pilus (TCP), two main virulence factors required for disease. CT and TCP expression is controlled by the transcriptional activator protein toxT. Results of a study revealed a previously unknown regulatory mechanism consisting of an RNA thermometer that controls temperature-dependent translation of toxT, facilitating V. cholerae virulence at a relevant environmental condition found in the human intestine (Proc Natl Acad Sci U S A. 2014 Sep 16. pii: 201411570. [Epub ahead of print])

The Florida Department of Health in Hillsborough County, USA, reported an increase in cryptosporidium cases since 1 July 2014. Public health officials say that 157 cases have been reported by DOH-Hillsborough in the last 2 months. In 2013, there were only 11 cases during the same time period. (http://foodpoisoningbulletin.com/2014/cryptosporidium-outbreak-in-hillsborough- county-florida/). Clinical microbiology laboratories rely on quantitative PCR for its speed, sensitivity, specificity and ease of use. However, it requires the use of a standard curve. Droplet digital PCR provides absolute quantitation without the need for calibration curves. A comparison between droplet digital PCR and quantitative PCR-based analyses was conducted for the enteric parasite, Cryptosporidium. The precision of droplet digital PCR was consistently better compared with quantitative PCR. For most templates analysed including Cryptosporidium-positive faecal DNA, the sensitivity of both methods was comparable. A cost analysis based on 96 samples revealed that the overall cost (consumables and labour) of droplet digital PCR was two times higher than quantitative PCR (Int J Parasitol. 2014 Sep 16. pii: S0020-7519 (14) 00226-4. doi: 10.1016/j.ijpara. 2014.08.004. [Epub ahead of print])

The total number of probable, confirmed, and suspected cases in the current outbreak of Ebola virus disease (EVD) in West Africa was 5335, with 2622 deaths, as at the end of 14 September 2014. Countries affected are Guinea, Liberia, Nigeria, Senegal and Sierra Leone. (http://apps.who.int/iris/bitstream/10665/133833/1/roadmapsitrep4_eng.pdf?ua=1). In an attempt to estimate the case fatality rates of Zaire, Sudan and Bundibugyo Ebola species, a meta-analysis was performed of World Health Organisation's data on outbreaks of infections due to these species. Twenty outbreaks, including the current one, were studied. The estimated case fatality rate was 65.4% (CI 95% (54.6%; 75.5%)) and varied among the outbreaks. A species effect was identified, with a higher case fatality rate for the Zaire species than for Sudan and Bundibugyo species. The case fatality rate of the Zaire species tended to decrease with time (Med Mal Infect. 2014 Sep 2. pii: S0399-077X (14) 00208-X. doi: 10.1016/j.medmal. 2014.08.005. [Epub ahead of print])

In order to characterise the Ebola viruses in the current outbreak, Ebola virus genomes from 78 patients in Sierra Leone were examined. A rapid accumulation of interhost and intrahost genetic variation was observed, thus enabling characterisation of patterns of viral transmission over the initial weeks of the epidemic. It was concluded that this West African variant probably diverged from central African lineages around 2004, crossed from Guinea to Sierra Leone in May 2014, and subsequently exhibited sustained human-to-human transmission, with no evidence of additional zoonotic sources. The study also concluded that, since many of the mutations alter protein sequences and other biologically meaningful targets, they should be monitored for impact on diagnostics, vaccines and therapies, which are all critical parts of outbreak response (Science. 2014 Sep 12;345 (6202):1369-72

A team from the Centre for Values, Ethics and Law in Medicine, University of Sydney, Sydney, NSW, Australia, has expressed their ire at the politics/policies related to the current Ebola virus outbreak (Med J Aust. 2014 Sep 15;201 (6):352-4). They contend that the unprecedented extent of mortality and morbidity in this outbreak has resulted more from the imposition of neoliberal economic policies on the countries affected than from the biological virulence of Ebola virus. They feel that the lack of vaccines and medications for Ebola virus disease is evidence that markets cannot reliably supply treatments for epidemic diseases. They attribute the current difficulties in containment chiefly to the erosion or non-development of the health and medical infrastructure needed to respond effectively, as a direct result of market-privileging policies imposed in the interests of wealthy nations. Food for thought.




 

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